Abstract:

Embryonic frontal cortex was implanted into the adult ratis motor area previously injured. Fiber between the transplant and the host brain tissue were traced by using WGA-HRP and the retrograde fluorescent dye both True Blue (TB) and Nuclear Yellow (NY) .Some grafts were shown to receive the afferent projections from many regions of the host brain: bilateral septum, hypothalamus and reticular formation, as well as ipsilateral striatum and thalamus, Axonal outgrowth from the transplanted neurons to several host brain areas occurred not onlv in the contralateral cortex,but also to the ipsilateral thalamus. In one case,outgrowth passed into con tralateral upper cervical spinal cord.In a few cases in which TB were injected into the con tralateral motor cortex and NY into ipsilateral thalamus, few double labeled cells with both TB and NY, which haven’t been seen in normal motor cortex, were found in the grafts. These data suggest that homotypic implants of embryonic brain tissue can, in some ways, replace damaged cortical projections and may eventually be able to reconstitute normal cortical circuitry.